But there are physics problems. The unsprung mass ratio is the biggest one. The lighter the vehicle the worse this problem becomes. The wheel is unable to hit a small bump and move up over it because it's got so much mass as compared to a "normal" car. When you hit a large bump and it moves up, it stays up for a long time, and this means the tire is no longer in contact with the road. So you get a terrible ride quality, and can lead to outright dangerous handling if these are in the front (steering) wheels, as any wheel hop means you lose steering input. Also, because the rest of the car is lighter because it doesn't have any motors on board (sprung mass), all the wheel movements affect the body even more, and since the wheel is relatively heavy, it is able to impart much more force on the body.
There are other physics and mechanical issues, such as maintaining an efficient gap is really difficult, and it's also exposed to much more vibration and dirt. Then there are the problems with mechanical brakes, where do they go and how do they interface, etc, and you have heat from the brakes bleeding into the motor, etc. On Mon, Jul 17, 2023 at 1:29 PM Ryan Fulcher via EV <ev@lists.evdl.org> wrote: > Or maybe, and try to stick with me here, just maybe, this company that has > spent tons of money up front on research and development that has test > articles which achieve <100Wh/mile at freeway speeds has somehow engineered > high quality hub motors. I don;t think there is anything in physics which > dictates that hub motors are impossible to "get right" for automotive yes. > Sure there are plenty of examples of poorly implemented or designed hub > motors in the past, Lordstown using (perhaps these same Elaphe?) motors but > on a multi ton pickup truck is an example of a poor implantation? I can't > say for sure, and we have all heard the pros and cons of unsprung mass etc > etc. But I am also hearing a lot of glossing over the benefits of such > motor packaging, which if you looked at the body design of the Aptera, > their offroad three motor version just can not work be bringing these > motors inboard. Anyway, perhaps we will get to experience one first hand > within a year or so. Just remember that everything was impossible until it > was not, so long as physics allows. > > On Sun, Jul 16, 2023 at 4:51 PM (-Phil-) via EV <ev@lists.evdl.org> wrote: > > > Then you call it a normal motor! > > > > And instead of making a lot of poles and super high currents > (inefficient) > > to get reasonable torque like most hub motors, you can put a gear > reduction > > in and now you are like most all production EVs. Most use a single > motor, > > gear reduction, then a differential. Some like the Lucid Air and the > Tesla > > Plaid use dual motors, one for each side, so just the motor and gear > > reduction. Then you get to do torque vectoring as well. > > > > On Sun, Jul 16, 2023 at 4:18 PM Robert Johnston via EV < > ev@lists.evdl.org> > > wrote: > > > > > I wonder if you could take hub motors and mount them inboard, so > instead > > of > > > a differential you'd have back-to-back "hub"motors connected to > > > driveshafts. So you don't have the unsprung weight of hub motors, but > you > > > do get the advantages of electronically controllable torque per wheel. > > > > > > On Sun, 16 Jul 2023 at 16:58, Josh Landess via EV <ev@lists.evdl.org> > > > wrote: > > > > > > > it does sound like a shame they went with hub motors. Otherwise, the > > > > vehicle is something I could consider buying. Well, I'll keep an eye > > > > out for early owner reports and maybe if they seem "ok", I'll still > > > > consider it someday. Or maybe if the company gets harsh feedback > from > > > > owners it will redesign the vehicle to incorporate non-hub motors. > > > > > > > > > > > > On 7/11/2023 4:57 AM, jerry freedomev wrote: > > > > > Hi Josh and All, > > > > > Hub motors are bad for 2 reasons, they have little start up > torque > > > > > and to make up for they require heavy powerful motors. > > > > > They are great in non suspension Ebikes, etc where it can be much > > > > > smaller as gets help with a leg push/pedal for starting up. > > > > > As a lightweight EVer I was wondering how bad the unsprung weight > > > > > would be with the Aptera. Indications came from a Jay Leno drive > > vid > > > > > in one the fixed camera showed it to be noticeable to me but not > bad. > > > > > I'd keep it on smoother roads when possible as I do with my light > > EVs. > > > > > I'd suggest a good seat, it shouldn't be a problem. Too bad they > > went > > > > > complicated when the original design with a geared rear motor > instead > > > > > it would cost much less to build and better handling, more starting > > > > > power could be in production. > > > > > Jerry Dycus > > > > > > > > > > On Sunday, July 9, 2023 at 10:37:54 PM PDT, Josh Landess via EV > > > > > <ev@lists.evdl.org> wrote: > > > > > > > > > > > > > > > I hadn't noticed that they were using the hub motors, thanks for > > > > > pointing this up. I will be a bit more cautious before I consider > > > > > getting one, though I'll still keep open the possibility. On top of > > the > > > > > other risks they seem to be asking from their pioneer first > > customers, > > > > > that one seems like a notable one. > > > > > > > > > > On 7/9/2023 5:14 PM, Alan Arrison via EV wrote: > > > > > > Thanks for those informative videos. It still isn't real world > > data. > > > > > > > > > > > > There is a reason nobody is using wheel motors on highway capable > > > > > > vehicles. > > > > > > > > > > > > > > > > > > On 7/8/2023 8:51 PM, Ryan Fulcher wrote: > > > > > >> So this? > > > > > >> https://youtu.be/CqPMtEIT3f4 > > > > > >> > > > > > >> Or this: > > > > > >> https://youtu.be/1alRUqx9UX8 > > > > > >> > > > > > >> > > > > > >> On Sat, Jul 8, 2023, 17:46 Alan Arrison via EV < > ev@lists.evdl.org > > > > > > > > >> wrote: > > > > > >> > > > > > >> I was excited about the Aptera until I saw the hub motors. > > > > > >> > > > > > >> I'll pass until I see some real world reliability > > demonstrated. > > > > > >> > > > > > > -------------- next part -------------- > > > > > > An HTML attachment was scrubbed... > > > > > > URL: > > > > > > > > > > > < > > > > > > > > > > http://lists.evdl.org/private.cgi/ev-evdl.org/attachments/20230709/03646ce3/attachment.htm > > > > > > > > > > > _______________________________________________ > > > > > > Address messages to ev@lists.evdl.org > > > > > > No other addresses in TO and CC fields > > > > > > HELP: http://www.evdl.org/help/ > > > > > > > > > > > > > > > > _______________________________________________ > > > > > Address messages to ev@lists.evdl.org > > > > > No other addresses in TO and CC fields > > > > > HELP: http://www.evdl.org/help/ > > > > > > > > > -------------- next part -------------- > > > > An HTML attachment was scrubbed... > > > > URL: < > > > > > > > > > > http://lists.evdl.org/private.cgi/ev-evdl.org/attachments/20230716/56eebc86/attachment.htm > > > > > > > > > _______________________________________________ > > > > Address messages to ev@lists.evdl.org > > > > No other addresses in TO and CC fields > > > > HELP: http://www.evdl.org/help/ > > > > > > > > > > > > > > -- > > > Robert "Anaerin" Johnston > > > -------------- next part -------------- > > > An HTML attachment was scrubbed... > > > URL: < > > > > > > http://lists.evdl.org/private.cgi/ev-evdl.org/attachments/20230716/3be53300/attachment.htm > > > > > > > _______________________________________________ > > > Address messages to ev@lists.evdl.org > > > No other addresses in TO and CC fields > > > HELP: http://www.evdl.org/help/ > > > > > > > > -------------- next part -------------- > > An HTML attachment was scrubbed... > > URL: < > > > http://lists.evdl.org/private.cgi/ev-evdl.org/attachments/20230716/efe7a9ee/attachment.htm > > > > > _______________________________________________ > > Address messages to ev@lists.evdl.org > > No other addresses in TO and CC fields > > HELP: http://www.evdl.org/help/ > > > > > -------------- next part -------------- > An HTML attachment was scrubbed... > URL: < > http://lists.evdl.org/private.cgi/ev-evdl.org/attachments/20230717/1e69d86c/attachment.htm > > > _______________________________________________ > Address messages to ev@lists.evdl.org > No other addresses in TO and CC fields > HELP: http://www.evdl.org/help/ > > -------------- next part -------------- An HTML attachment was scrubbed... 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